File Name: cpld and fpga architecture and applications notes .zip
The proposed architecture adds the feature of reconfiguration to structured ASIC with both static and dynamic reconfiguration options. Static reconfiguration is realized using the possibility to reprogram the SRAM based look-up tables at power-up while dynamic reconfiguration uses embedded memory to implement a multi-context device. Dynamic reconfiguration is realized by storing sixteen CPLD configurations in on-chip memory.
- Digital Systems Design With Fpgas And Cplds Pdf
- Cpld and fpga architecture applications previous question papers
- UNIT III : CPLD & FPGA ARCHITECTURE & APPLICATIONS
The configuration of the FPGA architecture is generally specified using a language, i.
Digital Systems Design With Fpgas And Cplds Pdf
Here the term programmable indicates an ability to program a function into the chip after completion of silicon fabrication. This is possible by the programming technology, which is a method that can cause a change in the behavior of the pre-fabricated chip after fabrication, in the field, where system users create designs. The first programmable logic devices used very small fuses as the programming technology. Programming Technologies There are a number of programming technologies that have been used for reconfigurable architectures.
Each of these technologies have different characteristics and have significant effect on the programmable architecture. Some of the well-known technologies are i. These devices use static memory cells which are divided throughout the FPGA to provide configurability. An example of such memory cell is shown below. To program the routing interconnect of FPGAs which are generally steered by small multiplexors. Narasimmha Murthy Ph. D yayavaram yahoo. There are two primary uses for the SRAM cells.
Most are used to set the select lines to multiplexers that steer interconnect signals. Historically, SRAM cells were used to control the tri-state buffers and simple pass transistors that were also used for programmable interconnect. SRAM-based programming technology has become the dominant approach for FPGAs because of its re-programmability and the use of standard CMOS process technology and therefore leading to increased integration, higher speed and lower dynamic power consumption of new process with smaller geometry.
There are however a number of drawbacks associated with SRAM-based programming this technology. For example an SRAM cell requires 6 transistors which makes costly in terms of area compared to other programming technologies.
Further SRAM cells are volatile in nature and external devices are required to permanently store the configuration data. There is a problem in terms of security of data also. Since the configuration information must be loaded into the device at power up, there is the possibility that the configuration information. To overcome this problem certain encryption techniques are followed. Electrical properties of pass transistors are not ideal. However, they are far from ideal switches as they have significant on-resistances and present an appreciable capacitive load.
As FPGAs migrate to smaller device geometries these issues may be exacerbated. Flash Programming Technology An important alternative to the SRAM-based programming technology is the use of flash or technology inject charge onto a gate that. These cells are non-volatile; they do not lose information when the device is powered down. With modern IC fabrication processes, it has become possible to use the floating gate cells directly as switches. Flash memory cells, in particular, are now used because of their improved area efficiency.
The widespread use of flash memory cells for non-volatile memory chips ensures that flash manufacturing processes will benefit from steady decreases in process geometries. Flash-based programming technology offers several advantages. For example, this programming technology is nonvolatile in nature. Flash-based programming technology is also more area efficient than SRAM-based programming technology. Flash-based programming technology has its own disadvantages also. Also, flash-based technology uses non-standard CMOS process.
This flash-based programming technology offers several unique advantages, most importantly non-volatility. This feature eliminates the need for the external resources required to store and load configuration data when SRAM-based programming technology is used.
Additionally, a flash-based device can function immediately upon power-up instead of having to wait for the loading of configuration data. The flash approach is also more area efficient than SRAM-based technology which requires up to six transistors to implement the programmable storage.
The programming circuitry, such as the high and low voltage buffers needed to program the cell, contributes an area overhead not present in SRAM-based devices. However, this cost is relatively modest as it is amortized across numerous programmable elements. In comparison to 3. The use of a floating-gate to control the switching transistor adds design complexity because care must be taken to ensure the sourcedrain voltage remains sufficiently low to prevent charge injection into the floating gate.
Since newer processes require lower voltage levels, this issue may become less of a concern in the future. One disadvantage of flash-based devices is that they cannot be reprogrammed an infinite number of times.
Charge buildup in the oxide eventually prevents a flash-based device from being properly erased and programmed. For most of the uses of FPGAs ,this programming count is more than sufficient. In many cases FPGAs are programmed for only one use. Another significant disadvantage of flash devices is the need for a non-standard CMOS process. Also, like the static memory-based technology, this programming technology suffers from relatively high resistance and capacitance due to the use of transistor-based switches.
One trend that has recently emerged is the use of flash storage in combination with SRAM programming technology. In devices from Altera, Xilinx and Lattice, on-chip flash memory is used to provide nonvolatile storage while SRAM cells are still used to control the programmable elements in the design. This addresses the problems associated with the volatility of pure-SRAM approaches, such as the cost of additional storage devices or the possibility of configuration data interception, while maintaining the infinite re-configurability of SRAM-based devices.
However, the incorporation of flash memory generally means that the processing technology will not be as advanced as pure-SRAM devices. This technology is based on structures which exhibit very high-resistance under normal circumstances but can be programmably blown in reality, connected to create a low resistance link.
An anti-fuse is a two terminal device with an unprogrammed state presenting a very high resistance between its terminals. When a high voltage from 11 to 20 volts, depending on the type of anti-fuse is applied across its terminals the anti-fuse will blow and create a low resistance link.
This link is permanent. Programming an anti-fuse requires extra circuitry to deliver the high programming voltage and a relatively high current of 5 mA or more. This is done in through fairly sizable pass transistors to provide addressing to each anti-fuse. A major advantage of the anti-fuse is its small size, little more than the cross-section of two metal wires. But this advantage is limited by transistors, which the large size of the necessary programming.
A second major advantage of an anti-fuse is its relatively low series resistance. The on-resistance of the ONO anti-fuse is to ohms, while the amorphous silicon anti-fuse is 50 to ohms. Additionally, the parasitic capacitance of an un programmed amorphous anti-fuse is significantly lower than for other programming technologies. The limitations of this technology are , this technology does not make use of standard CMOS process.
Also, anti-fuse programming technology based devices cannot be reprogrammed. The ideal technology should be re-programmable, non-volatile, and that uses a standard CMOS.
But it is clear that none of the above technologies satisfy these conditions. However, SRAM-based programming technology is the most widely used programming technology. The main reason is its use of standard CMOS process. Due to this reason it is expected that this technology will continue to dominate the other two programming technologies. The first modern-era FPGA was introduced with 64 logic blocks and 58 inputs and outputs.
This was the most successful family of FPGAs. The XC archtecture includes enhancements to the XC architecture to improve performance ,density and usability. The XC architecture was developed with manual tools for design implementation and the architecture also shows a bias towards manual design.
Device speeds, described in terms of maximum guaranteed toggle frequencies, range from 70 to MHz. The XC Configurable Logic block is substantially larger than XC and Each of the lookup tables has four inputs and requires 16 bits of configuration memory.
The two lookup tables can be combined with a multiplexer to produce any function of five inputs and some functions of up to seven inputs. All four families share a common architecture, development software, design and programming methodology, and also common package pin-outs. The XCL is the right solution for battery-operated and low-power applications.
While both families are bit stream and footprint compatible, the XCA family extends toggle rates to MHz and in-system performance to over 80 MHz. The details of XC family of devices are given below in the table. In addition to this a small amount of configurable memory is also present. The important addition in this is a flip-flop in the out-put path. By registering the data in IOB ,the clock to-out- time does ot include interconnect delays.
The result is a fast ,predictable clocked output. The XC IOB also includes a programmable pull up, optional output inversion and selectable slew rate. Input from the pad can be brought into the interior of the chip either directly or registered or both.
Each user-configurable IOB as shown below, provides an interface between the external. Each IOB includes both registered and direct input paths. Each IOB provides a programmable 3-state output buffer, which may be driven by a registered or direct output signal. Configuration options allow each IOB an. Each input circuit also provides input clamping diodes to provide electrostatic protection, and circuits to inhibit latch-up produced by input currents.
A choice of two clocks is available on each die edge. The polarity of each clock line not each flip-flop or latch is programmable. A clock line that triggers the flip-flop on the rising edge is an active Low Latch Enable Latch transparent signal and vice versa. Passive pullup can only be enabled on inputs, not on outputs.
Each of the look-up tables has four inputs rather than three and hence requires sixteen bits of configuration memory rather than eight. The lookup tables can be combined with a multiplexer to produce any function of five inputs and some functions of up to seven inputs.
Cpld and fpga architecture applications previous question papers
Electronic companies design the hardware dedicated to their products with their standards and protocols which makes it challenging for the end users to reconfigure the hardware as per their needs. This requirement for hardware led to the growth of a new segment of customer-configurable field programmable integrated circuits called FPGAs. It is a type of device that is widely used in electronic circuits. FPGAs are semiconductor devices which contain programmable logic blocks and interconnection circuits. It can be programmed or reprogrammed to the required functionality after manufacturing.
Here the term programmable indicates an ability to program a function into the chip after completion of silicon fabrication. This is possible by the programming technology, which is a method that can cause a change in the behavior of the pre-fabricated chip after fabrication, in the field, where system users create designs. The first programmable logic devices used very small fuses as the programming technology. Programming Technologies There are a number of programming technologies that have been used for reconfigurable architectures. Each of these technologies have different characteristics and have significant effect on the programmable architecture. Some of the well-known technologies are i.
Circuit diagrams were previously used to specify the configuration, but this is increasingly rare due to the advent of electronic design automation tools. FPGAs contain an array of programmable logic blocks , and a hierarchy of "reconfigurable interconnects" allowing blocks to be "wired together", like many logic gates that can be inter-wired in different configurations. Logic blocks can be configured to perform complex combinational functions , or merely simple logic gates like AND and XOR. In most FPGAs, logic blocks also include memory elements , which may be simple flip-flops or more complete blocks of memory. FPGAs have a remarkable role in embedded system development due to their capability  to start system software SW development simultaneously with hardware HW , enable system performance simulations at a very early phase of the development, and allow various system partitioning SW and HW trials and iterations before final freezing of the system architecture.
A CPLD comprises multiple PAL-like blocks on a single chip with programmable interconnect to connect the blocks. ❑ CPLD Architecture. PAL-like block. PAL-like.
UNIT III : CPLD & FPGA ARCHITECTURE & APPLICATIONS
Field-Programmable Logic Devices Component function is defined by user under programcontrol Logic Cells are interconnected by programming Advantages: Flexible design that changes byreprogramming, ease of designchanges Reduce prototype-product time Large scale integration over, gates Reliability increased, low financialrisk Smaller device, low start-up cost3 4. The chart serves as a guidefor selecting a device for anapplication according to thelogic capacity needed.
What is FPGA?
Programmable Logic Device Wikipedia. Field Programmable Logic Sciencedirect. Field Programmable Gate Array Wikipedia. Digital System Design 2 Be Electronics. Design Flow And Methodology.
Increasing demand for consumer electronics such as smartphones is expected to be the key driving force for the market over the next six years. Growing electronic content in automotives and penetration of Electric Vehicles EV What is the name of the most basic logic block inside a CPLD? Name five of the design blocks found in a typical FPGA chip architecture Authority is a the question of how national and state powers are related was largely settled by a the choice questions papers cpf assistant cpanel installation cpld and fpga architecture applications previous question papers craftsman snowblower 27 cracking the wall women in higher education Answers, cpld and fpga architecture applications previous question papers, guidelines for hazard evaluation procedures 3rd edition free download, massive ten book romance box set , la luce della notte.
Here the term programmable indicates an ability to program a function into the chip after completion of silicon fabrication. This is possible by the programming technology, which is a method that can cause a change in the behavior of the pre-fabricated chip after fabrication, in the field, where system users create designs. The first programmable logic devices used very small fuses as the programming technology. Programming Technologies There are a number of programming technologies that have been used for reconfigurable architectures. Each of these technologies have different characteristics and have significant effect on the programmable architecture.